I've taken a list of English words, and examined each of them to see what they sound like (using the PHP metaphone function). This page lists the most common metaphone codes, along with their words. You can also search for a word of your own, and see which words sound similar - and which ones rhyme, and which ones alliterate.
pensile pensil pencil penicil pencel penicillia
ensile pensile tensile enisle insole console mainsail moonsail pensil tonsil
pens peans peens peins penes penis pennies pennis pensee peonies peons opens spense